The recommended tension for that racquet is 50-60 lbs. So what do you want? control or power? If you're not sure, string it in the middle and go from there. If you find your balls are flying long all the time, then string higher (in increments of 2 lbs). If you can't hit the baseline to save your life, then string lower.

Thaks for the comment anubis... Actually I don't have the luxury of testing the right tension for this string... a friend of mine just gave this for free... I usually use an rpm blast on my k90 and KPS88 around 48-50lbs lower than the recommended tension of 50-60lbs.